v0.3.0: CI dotnet 8.0.424 pinned with isolated install

- Pin .NET SDK to 8.0.424 in all CI jobs to avoid floating channel drift

- Install SDK to runner temp via DOTNET_INSTALL_DIR to bypass

  C:\\Program Files\\dotnet overwrite/extract conflicts on Gitea Windows runners

- Simplify release job to dotnet publish + upload-artifact

- Exclude memory-bank/ via .gitignore (internal dev memory stays local)

src/RgbLedStripController/App.xaml.cs

@@ -0,0 +1,17 @@
+using System;
+using Velopack;
+
+namespace RgbLedStripController;
+
+public partial class App : System.Windows.Application
+{
+    [STAThread]
+    public static void Main(string[] args)
+    {
+        VelopackApp.Build().Run();
+
+        var app = new App();
+        app.InitializeComponent();
+        app.Run();
+    }
+}